The present invention relates to a digital contents generating apparatus and a digital contents reproducing apparatus using a network. More particularly, it relates to a digital contents generating apparatus in which identification data comprising specific information, i.e., electronic watermark data, are embedded in digital contents and the digital contents are then encrypted for delivery, and to a digital contents reproducing apparatus for the reproduction of such digital contents.
An increasing amount of digital contents is being provided. This is due, for example, to the explosive increase in the number of users of the World Wide Web (WWW) on the Internet, and the spread of hardware that allows personal access to large volumes of data. With the increase in the amount of digital contents provided, illegal reproduction of digital contents is becoming a social problem. As a technique for preventing such illegal reproduction, embedding and detection of electronic watermark data is gaining attention. The embedding of electronic watermark data involves embedding ID information that is imperceptible by humans but is machine-readable directly in the data constituting the digital contents as a kind of noise. The embedded ID information is characterized in that it exists with the digital contents at all times and cannot be easily erased or modified. These characteristics are taken advantage of by the electronic watermark data embedding and detection technique for preventing illegal reproduction of digital contents.
However, the digital contents such as image data in which electronic watermark data are embedded are by no means visually inferior to the original digital contents prior to the embedding of the electronic watermark data. Therefore, those who illegally obtained a data storage medium storing the digital contents with the embedded electronic watermark data can view or listen to the digital contents.
It is also noted that with the spread of the Internet, services are becoming more and more available in which authorized owners of digital contents distribute their contents to predetermined users via the Internet.